2010-09-01

Opportunity Sol 573 (Spirit Sol 591)

We're not finished being paranoid yet, so thisol's drive is still circumscribed. Callas had a 5m drive in mind, but a 5m drive would just take the rover a short way along a patch of outcrop -- it's hardly worth doing. We might as well cross the next ripple, and that's more like 10m. Somehow I manage to talk him into this, and over the ripple and through the woods, to Grandmother's house we go.

Er, or something like that.

I thought thisol would be a doddle, but it turns out to be a little more challenging than I'd expected. Not greatly so, but at least there's some original thinking required thisol. We're still copying from the sol 563/567 drive, and the next segment of that drive -- the one that takes us over the next ripple -- would leave us at a heading of 10 degrees. But that's relatively poor for comm; we need a heading of more like 65 degrees.

This change is not as simple as you might think. Back in the day, we'd just turn in place at the end of the drive. But on Opportunity, with her stuck right front steering actuator, the rules limit the size of point turns, this prohibiting this simple solution. Instead, we work out a way to modify Opportunity's heading before she crosses the ripple, which enables us to get her heading to 45 degrees. After she hops the ripple, she turns in place the remainder of the way.

This maneuver comes with problems of its own, though. Instead of leaving Opportunity heading more or less along the ripple, she's parked transverse to it. This is an uncomfortable position for a rover that can't do large point turns and can do sharp arcs only in one direction. But we keep plugging away, and manage to convince ourselves that a combination of sharp arcs and small point turns can get her back on track again. So we leave her there, with copious notes in this sequence about how the next one had probably better look.

The other thing that happens thisol -- well, first I have to tell you about my superstition. The two-weeks-to-Erebus thing doesn't count -- that's not a superstition, that's a law of nature. No, my superstition is that if you write the uplink report before the CAM, something will happen at the CAM that requires us to rebundle. Basically, it jinxes the CAM.

I've told Paolo (RP-2 thisol, shadowing Jeng) about this superstition, but he goes ahead and does it anyway. He has a good excuse -- he has to go help Mark Maimone get the SSTB rover back online -- but it availeth him not. Sure enough, during the CAM I notice an error in the RP sequence, which would cause us to record less drive data than we'd want -- part of our paranoia is that we want lots of this data, particularly when hopping ripples -- and we have to fix it and rebundle.

This superstition is well on its way to becoming a law of nature, too.